Nine mongrel dogs were used

five for control and four for experimental study. Experimental localized left ventricular myocardial infarction was produced by ligation of the branches of left circumflex coronaryartery and branches of left anterior descending coronary artery. Injectio Salviaemiltiorrhiza Composita 4 gm/kg and 5%glucose water 100 ml. was admiuistered to the experimental group

just before and six hoursafter the ligation

only 50% glucose water 100 ml. was administered to the control group

These dogs were sacrificed 24 hrs. after the ligation. Tissue blocks of 1 cubic mm were taken from the central

middle and peripheral zone of the infarction and were fixed in 1% phosphate-buffered osmium tetraoxide

stained with uranium actate en bloc

dehydrated and embedded in Epon 618. These sections were stained willl lead citrate. The experimental and the control groups had the same kinds of the pathological changes of capillaries

such as degeneration or necrosis of endothelia

stasis

thrombosis and collapse of the capillary lumen

Besides

in manycapillary walls of both groups

the endotbelia showed intraluminal and/or extraluminal projections

along which no basal lamina was seen. The intraluminal projections were of various kinds. Presumably

both intraluminal and extraluminal projections are non-specific proliferative pathological reactions and their pathological significance are discussed. At the same time

a larger section

from each of the two blocks of the peripheral zone

was prepared from every dog. The sections were moumted on single-hole grids

and at the

electron optic enlargemenl of 10

000 times

the profiles of capillaries could be differentiated into two varieties

one with the pathological changes and the other without. The number of capillaries with the pathological changes in the experimental group isless than that of the control group

and the difference is statistically significant

P<0.05. It is concluded that the number of capillaries with the pathological changes on the border of the infarction is less after the administration of Injectio Salviae miltiorrhiza Gomposita.